This invention relates in general to control cable actuation devices, and more particularly, to actuation devices including an adjustment device for Bowden-type (cable within a housing) control cables for bicycles or similar handlebar-steered vehicles.
Conventionally, a bicycle control cable assembly, including a control cable partially encased by a cable housing, is interposed between an operating mechanism such as a bicycle brake, derailleur or internal gear hub, and an actuation device such as a shifter or brake lever. In a bicycle derailleur, the control cable links the shifter to a derailleur having a chain guide for switching a drive chain laterally between sprockets of a multistage sprocket assembly. Derailleur shifters are generally available in two varieties: conventional pivoting levers and rotational twistshifters. Derailleur shifters are manually actuated to laterally displace the chain guide and in turn the drive chain to the desired sprocket. Repeated shifting, however, tends to both compress the cable housing and stretch out the control cable resulting in a change in relative length or slack between the control wire and the cable sheath. This slack in the control cable may cause the chain guide to urge the drive chain into a “rasping” zone between sprockets or may even result in undesired shifts.
In a conventional brake actuation device, a brake lever is pivotally mounted to a base member attached to a bicycle handlebar and a control cable extends from the brake lever to the brake mechanism. The brake pivots between an actuated position whereby the brake shoes engage the wheel rim, and an unactuated position whereby the brake lever is released to space apart the brake shoes from the wheel rim. This spacing is conventionally adjusted by a cable adjustment device, commonly a “barrel adjuster,” threadably connected to the base member and configured to engage the cable housing to change the effective length of the cable between the lever and the brake mechanism. Slack in brake control cables widens the spacing or gap between the brake shoes and the wheel rim thereby requiring greater brake lever deflection to initiate braking and will generally alter the brake “feel.” This may result in a potentially hazardous situation whereby a rider accustomed to brake shoe contact after deflecting the brake lever a given distance may overcompensate and unintentionally lock the brakes, inducing a skid. It is therefore desirable to incorporate an adjustment device into a control cable system to eliminate excessive cable slack and precisely tune shifting and braking devices.
Conventionally, a barrel adjuster and a brake lever are separately attached to the base member which is in turn attached to the bicycle handlebar. The brake lever is rotatable about a first axis to actuate the braking mechanism to displace the brake shoes against the wheel rim to slow the bicycle. The barrel adjuster is separately rotatable about a second axis to adjust the gap between the brake shoes and the wheel rim in the unactuated position of the braking device. It is therefore desirable to provide an actuation lever that is rotatable about a first axis to actuate the operating mechanism, in the case of a brake mechanism to displace and urge the brake shoes against the wheel rim to slow the bicycle, and rotatable about a 2nd axis to adjust the effective cable length, in the case of a brake mechanism to adjust the gap between the brake shoes and the wheel rim in the unactuated position.